Observations on the Reproductive Biology of Miconia calvescens DC (Melastomataceae), an Alien Invasive Tree on the Island of Tahiti (South Pacific Ocean)¹

Abstract

Miconia calvescens DC (Melastomataceae) is a dominant invasive species in the tropical oceanic island of Tahiti (French Polynesia, South Pacific Ocean), where it was introduced as an ornamental plant. Whereas this small tree is sparse in its native range of Central America, it has spread in Tahiti into a wide variety of habitats including native wet forests. The remarkable success of this invasion is due in great part to prolific reproduction: a mature tree can bear up to 220 inflorescences with an average of 1330 flowers/inflorescence, 208 fruits/infructescence and 195 seeds/fruit. Two and a half years of phenological observations in a highly invaded site indicated that three major peaks of flowering occur/year over brief periods: flower anthesis lasted a few days and pollen grain germination suggested a short stigmatic receptivity of only a few hours; no pollinators were observed foraging on flowers during our survey; the production of fruits containing viable seeds in bagged inflorescences showed that self‐fertilization can occur; pollen‐ovule ratio (log P/O = 2.68) suggested facultative xenogamy; bagged isolated flowers to test for autogamy and style cutting to learn whether apomixis occured or not were not conclusive. The flowering phenology and the breeding system of M. calvescens enable this plant to build up rapidly successful populations from even a single propagule on the island of Tahiti and on other sites of introduction. The vegetation structure of Polynesian native forests compared to Neotropical rain forests probably plays an important role in determining the reproductive success of M. calvescens and could provide a complementary explanation of the biological invasion processes in tropical oceanic islands.

Economic lessons from control efforts for an invasive species: Miconia calvescens in Hawaii

“…Though the growth rate has been estimated heuristically, we do not expect that it differs from 0.3 significantly. This rate also conforms closely to the actual expansion of the tree on Tahiti, from a single tree in 1937 to dense monotypic stands covering 70,000 ha in the early 1990s, though theoretically the tree is capable of spreading at a much higher rate (Meyer, 1998a).…”

Biologia reprodutiva de Miconia angelana (Melastomataceae), endêmica da Serra da Canastra, Minas Gerais

“…(Mori & Pipoly 1984) e M. calvescens DC. (Meyer 1998). Porém, essas duas espécies apresentam fl oração mais sincrônica e limitada no tempo, referida na literatura como big bang, enquanto em M. angelana a fl oração apresenta múltiplos episódios ao longo de quase um mês, o que indicaria uma fl oração do tipo múltiplo bang (Gentry 1974).…”

Reproductive phenology of Miconia mirabilis (Melastomataceae) within three distinct physiognomies of Atlantic Forest, Bahia, Brazil

“…We did not find any correlations between flowering and fruiting with precipitation levels in the study areas. In fact, in seasonal tropical forests, the main factor triggering the flowering and fruiting are differences in precipitation (Mori & Pipoly 1984, Meyer 1998, Aragão et al 2005, Santos et al 2010, but in areas with low seasonal climate photoperiod is indicated as the only mechanism that can be attributed to synchronous flowering (Borchert et al 2005). …”